Some mobile terminal devices comprise two display surfaces. In such mobile terminal devices, there may be a first screen state in which only one display surface of the two display surfaces is arranged facing outside, and a second screen state in which both display surfaces are arranged facing outside. When executing an application program, the user is able to execute the application program in each screen state. However, in the first screen state, the user is unable to use functions executed using the hidden screen. It is desirable to enable the user to easily use functions executed using the hidden screen while maintaining the first screen state.